In Thien Truong Stadium in northern Vietnam's Nam Dinh Province, Thailand entered the game with good control and led 1-0 with Patrick Gustafson's goal in the 33th minute. But the AFF Cup champions failed to maintain their solid game in the second half after center-back Jonathan Khemdee received a red card in the 42nd minute.
Bin Ahmad equalized for Malaysia in the 61st minute and his team enjoyed final victory thanks to an own goal by Thai defender Anusak Jaiphet in the extra minute.
Thailand brought to Vietnam many young talents who are playing in Europe with a clear goal of winning the gold medal.
They used all three over-23-year-old players allowed in the game with Malaysia, showing determination to earn three points in the first game over the weaker opponents, who only used U23 players.
ESPN expert Gabe Tan has said Thailand were the top gold medal contenders this year, ahead of hosts Vietnam.
In SEA Games 2019 final, Vietnam beat Indonesia 3-0 to win gold. They played their opening game at this year SEA Games Friday and Vietnam earned a 3-0 victory.
Vietnam will play the Philippines next at 7 p.m. Sunday. The game will be reported live on VnExpress International.